New England Revolution drafted Riley in the second round of the 2005 MLS SuperDraft, and he acquitted himself well in his rookie season, playing various positions and scoring a goal. He continued to keep himself in the mix in defense, starting the majority of the games in 2006 and 2007.

Riley won his 5th US Open Cup title in 2013 with D.C. United. In the sixth minute of stoppage time there was on open header in the box from Álvaro Saborío that Riley was able to deflect onto the cross bar to prevent extra time.[5]

After his release from D.C. United, Riley trialled with and was eventually signed by LA Galaxy.[6]